Apparatus for automatically producing tissue slides

ABSTRACT

An apparatus and method for producing tissue slides is disclosed. The apparatus includes a holding assembly for manipulating the sample block, a blade assembly for preparing a thin section from the sample block, and a transfer roller mechanism for transferring the thin section to a receiving medium. The apparatus further includes a controller that may track the sample block and thin section. The method includes the steps of first locating a sample embedded within a support medium, which may be paraffin or a similar medium. Next, the embedded sample is oriented in such a way that its working surface is presented. This orientation may entail determining the orientation of the embedded sample with respect to the blade that will produce the largest cross-sectional area. Next, a slice of the sample from said embedded sample is removed and subsequently transferred to a suitable receiving medium, which may include a microscope slide.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates generally to the field of histology. Inparticular, the present invention is directed to an apparatus and methodfor automatically producing tissue slides.

2. Description of Related Art

Histology, the study of the groups of tissues found in mostmulticellular plants and animals, often requires that the plant oranimal tissue be provided in thin sections for study. One knowntechnique to create thin sections of tissue is through the use of amicrotome. The function of the microtome is simplistic and very muchlike that of any mechanical slicer which carves a pre-set measured sliceand retains and advances that unit of measure for each subsequentcutting cycle. The cutting results are very much dependent upon atechnician's practical skill.

Typically, tissue samples for general pathology examination aresurrounded by a support medium and manually molded into standardizedblocks. Paraffin is a known and commonly-used as a support medium.TissueTek O.C.T., manufactured by Sakura Finetek and available from VWRScientific, West Chester, Pa., may also be used as a support medium. Theoptimum cutting temperature (O.C.T.) formulation of water-solubleglycols and resins in TissueTek O.C.T. provides a convenient specimenmatrix for cryostat sectioning at temperatures of −10° C. and below.Resins and polymers, such as methacrylates, may also be used as supportmedia. Although resins and polymers are primarily used for electronmicroscopy, they can also be used for standard microscopy with someadjustments for hardness of the final product. Suitable resins andpolymers, including Araldite 502 Kit, Eponate 12™ Kit, and GlycolMethacrylate (GMA) Kit, are available from Ted Pella, Inc., Redding,Calif.

The tissue sample is manipulated in a metal support medium block mold bythe technician so as to locate it close to what will become the topcenter surface of the support medium block. This top surface thenbecomes the working surface of the sample block. The sample blockpreparation process will be described using paraffin as the supportmedium.

As the tissue sample is being located and set within the support mediumblock mold, melted paraffin is added. The paraffin cools and hardensinside the block mold; and as it does, a plastic holder is inserted. Inthe hardening process, the bottom half of the paraffin block becomeslocked within the frame of the plastic holder which becomes the base ofthe sample block. A technician then transfers the sample block to amicrotome to prepare very thin sections of the tissue sample for laterobservation.

The prepared sample blocks are manually locked into an adjustable clampassembly of the microtome. The technician can make limited manualadjustments to the clamp assembly in order to present the sample block'sworking surface to the microtome's cutting blade at an angle judged tobe most favorable to yielding the best possible sample slice. The clampadjustment for a given sample block is a subjective choice based on thejudgement and experience of the technician.

The technician can make additional microtome adjustments that pre-setthe starting lineal distance between the clamp assembly and the assemblyholding the cutting blade, as well as the thickness of the sample sliceeach time the clamp assembly is cycled by moving it past the bladeassembly. There is also limited adjustment of the angle of the cuttingblade as presented to the clamp assembly; however, the optimum settingof the blade is typically about 45 degrees from vertical.

One sample slice is the product of one microtome cycle. Once atechnician selects the orientation of the sample block's working surfaceto the cutting blade assembly's cutting blade, several cutting cyclesare required to advance the cutting blade into the block to a workingsurface depth, where the slices then taken are suitable for slideapplication. These slices may be referred to as histologic grade slices,which are slices that a pathologist or other professional would find ofacceptable quality for examination purposes. In particular, histologicgrade slices are slices of a relatively uniform thickness without anysignificant tears, folds, wrinkles, or contamination from unrelatedspecimens or other artifacts. Histologic grade slices are substantiallyflat and smooth.

When a suitable sample depth is acquired, the technician may cycle theclamp (with the sample block locked within) one to several times toobtain a series of histologic grade slices. After each slice, amechanism in the microtome advances the block toward the knife by thedesired slice thickness, which may be set by the technician. A typicalslice thickness is about 4 to 8 microns, but may vary from 1 to morethan 10 microns.

The technician places the slices onto the surface of warm water, locatedin a pan next to the microtome. The tissue sample, still secured in itsparaffin matrix, floats on the surface of the water. The warmth of thewater softens the paraffin, thereby removing wrinkles or otherdistortions in the slice. The technician may also move a sample sliceabout on the surface of the water to facilitate this result.

Once the technician judges that the floating tissue/paraffin matrixsample has the desired flat form, the technician brings a receivingmedium, such as a microscope slide, up under the portion of the floatingsample slice that captures the full tissue specimen. Repetitive successin this, again, depends upon the skill of the technician. The slide withsample is then set aside for drying, staining and evaluation, or forvarious molecular or histochemical analysis.

Occasionally, such as during performance of surgical procedures, it maybe necessary to get a rapid diagnosis of a pathologic process. Forexample, a surgeon may want to know if the margins of his resection fora malignant neoplasm are clear before closing, or an unexpected diseaseprocess may be found and require diagnosis to decide what to do next, orit may be necessary to determine if the appropriate tissue has beenobtained for further workup of a disease process. This may accomplishedthrough use of a frozen section.

Frozen sections are performed with an instrument called a cryostat. Thecryostat is essentially a refrigerated box containing a microtome. Thetemperature inside the cryostat is about −20 to −30° C. The piece oftissue to be studied is snap frozen in a cold liquid or cold environment(−20 to −70° C.). TissueTek O.C.T. would be a suitable support mediumfor frozen sections. The freezing makes the tissue solid enough tosection with a microtome. The tissue sections are cut and picked up on aglass slide. The sections are then ready for staining.

Although this process is effective, it is very time consuming and verydependent on the skill of the technician. As hospitals and laboratoriesseek to lower operating costs, they will seek to find more efficientways to accomplish inefficient tasks. Also, it is desirable to reducethe variation in sample preparation that may occur between differenttechnicians.

SUMMARY OF THE INVENTION

Therefore, a need has arisen for an improved apparatus and method forproducing histological slides.

It is an object of the present invention to automatically perform thecombined functions of the microtome and the technician.

It is a further object of the present invention to utilize mechanicalrobotic mechanisms to manipulate sample blocks and slides.

It is another object of the present invention to automatically determinethe optimal working surface of the tissue sample.

A method of producing thin sections from an embedded sample isdisclosed. In one embodiment, the method includes first locating asample embedded within a support medium, which may be paraffin or asimilar medium. Next, the embedded sample is oriented in such a way thatits working surface is presented. This orientation may entaildetermining the orientation of the embedded sample with respect to thecutting blade that will produce the largest cross-sectional area. Next,a slice of the sample from said embedded sample is removed andsubsequently transferred to a suitable receiving medium, which mayinclude a microscope slide.

In another embodiment, an apparatus for applying thin sections of atissue sample to a receiving medium is disclosed. The apparatus includesa slicing means for slicing thin sections from a tissue sample. Theslicing means typically includes one or more cutting blades for slicingthe tissue sample. The slicing means may include a first blade assemblythat slices the tissue sample to expose the tissue sample's workingsurface, and a second blade assembly for producing thin sections of thetissue sample. The apparatus further includes a plurality of transferrollers that are sequentially arranged in tangential proximity to eachother, such that a thin section on the surface of one transfer rollerwill be transferred to the surface of the sequentially successivetransfer roller. The first sequential transfer roller of is oriented inproximity to the slicing means so that a thin section sliced from saidtissue sample contacts the surface of the first sequential transferroller. A receiving medium is disposed in tangential proximity to afinal sequential transfer roller, so that a thin section on the surfaceof the final sequential transfer roller will be transferred to thereceiving medium in a substantially smooth and flat configuration.

In another embodiment, a method for applying thin sections of a tissuesample to a receiving medium is disclosed. The method includes firstslicing a thin section from a tissue sample. The slicing causes the thinsection to peel from the sample and adhere to a first transfer roller.Next, the thin section is transferred from the first transfer roller toan adjacent transfer roller that is in tangential proximity with thefirst transfer roller. Finally, the thin section is transferred from afinal transfer roller to a receiving medium that is in tangentialproximity with the final transfer roller. The thin section is placed onthe receiving medium in a substantially smooth and flat configuration.

In another embodiment, an apparatus for automatically producing tissueslides from a tissue sample within a sample block is disclosed. Theapparatus includes a holding assembly for manipulating the sample block,a blade assembly for preparing a thin section from the sample block, anda transfer roller mechanism for transferring the thin section to areceiving medium. The apparatus further includes a controller that maytrack the sample block and thin section.

Other objects, features, and advantages will be apparent to persons ofordinary skill in the art in view of the following detailed descriptionof preferred embodiments and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, the needssatisfied thereby, and the features and advantages thereof, referencenow is made to the following descriptions taken in connection with theaccompanying drawings in which:

FIGS. 1 a-b are a flowchart of a method for automatically producingtissue slides according to one embodiment of the present invention;

FIG. 2 schematic of the histologic grade slice blade and the transferrollers according to one embodiment of the present invention;

FIG. 3 is a perspective view of one embodiment of the present invention;

FIG. 4 is a top view of the embodiment shown in FIG. 3; and

FIG. 5 is a perspective view of the transfer roller assembly of theembodiment shown in FIG. 3.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention provides for automatically performing one or morefunctions of the microtome and the technician in the manual process formaking histologic slides, starting with the picking up and taking chargeof the sample block with its embedded tissue, to the finished sampleslide set aside for drying and staining. The invention utilizesmechanical robotic mechanisms which permit automatic manipulation ofsample blocks and slides, maintaining positive identification of thetissue samples and encoding slides, as well as the use of opticalimaging technology to locate the tissue sample within the sample block.Optical imaging technology may also be used to assist in the placementof the sample slice on the slide. All of the manipulations may beoperated and controlled by computer, inclusive of cataloguing sampleblocks and finished slides. In toto, the system of the present inventionwill standardize the process (especially relative to quality andproduction speed) and improve the collection, storage and output ofinformation relating to sample blocks and finished slides.

Preferred embodiments of the present invention and their advantages maybe understood by referring to FIGS. 1-5, like numerals being used forlike corresponding parts in the various drawings.

Referring to FIGS. 1 a-b, a flowchart depicting the process of thepresent invention is provided. First, in step 102, a tissue sample isprepared. As used herein, the term “tissue” refers to a solid mass whichis typically made up of biological cells, preferably from a human.However, the tissue is not limited to human tissue; it encompassesplant, animal, or any other tissue. The device of the present inventionmay also be used to create thin sections from samples of metals andother materials, so long as the hardness of the cutting blade exceedsthe hardness of the material being cut.

The tissue sample may be any sample for which microscopic examination ofthin sections is desirable. Procedures for collecting and handling suchsamples are well known in the art, and the sample may be prepared forsectioning by methods that are well-known in the art, such as byembedding the tissue sample in a suitable support medium, such as astandardized paraffin block, O.C.T., or resins and polymers, alldiscussed above.

The present invention will be discussed using paraffin as the supportmedium. The present invention, however, is not limited to using paraffinas the support medium. Any suitable support medium, including, but notlimited to, the known support medium discussed above, may also be used.Within the contemplation of this invention, other support media mayrequire minor variations in the method and apparatus of this inventionwhich are within the skill in the art in view of the guidance providedherein.

The prepared sample block may labeled with information about the sample,such as, inter alia, tissue sample control numbers, type of tissuesample, etc. Known input and labeling equipment may be used to input theinformation and to prepare the labels. The technician preparing thetissue sample may input information regarding the patient's name, typeof sample (i.e., what organ the sample came from), the number of slidesthat are to be made, clinical diagnosis, or any other relevantinformation, and may affix a label containing some or all of theinformation on the side or on the non-working surface of the sample. Theinformation may be fixed to the block in machine-readable form. Forexample, this information may be provided in a scannable bar code. Otherforms of storage, such as magnetic media, may also be used.Alternatively, a code affixed to the block may correlate withinformation about the sample stored external to the block, and the codemay facilitate access to the information.

Preferably, a sample block's code must be read before it can beprocessed. In the event a code can not be read, then the processingsequence may be stopped automatically. The technician could thenmanually eject the sample block in question, or the system could bepre-set to automatically eject any sample blocks for which the code isin any way suspect. In another embodiment, the technician may be able tooverride the system and continue the process despite the sample blockcode error.

In step 104, the sample is loaded in a holding assembly. This may bedone automatically, or it may be done manually. The holding assembly maysecure the sample block with several prongs; other means of holding thesample may also be used.

In one embodiment, a robotic clamp is used as a holding assembly. Therobotic clamp can move the sample through various processing stationsduring preparation of the thin sections for positioning on the slides.The robotic clamp may provide the ability to rotate the sample block inthree dimensions, which results in the optimum orientation of theworking surface of the tissue sample to the blade. In anotherembodiment, the robotic clamp may have the ability to rotate the blockin two dimensions. The rotation may be in set increments; for example,in increments of 2 degree arcs. Other suitable increments may also beused.

In another embodiment, negative pressure (a vacuum) may be used tosecure the sample. Because the sample blocks are generally of astandardized size, a vacuum clamp positioned on one side of the sampleblock may apply negative pressure. The sample block is then secured tothe vacuum clamp as long as negative pressure is applied. Any othersuitable holding devices may be used.

In step 106, the position of the tissue sample within the preparedsample block that is in the holding assembly is determined. In themanual process, the general angle of the tissue sample in the sampleblock is determined by the technician when the paraffin wax hardens. Inorder to achieve the best slice of the sample tissue, it is generallydesirable to present the maximum surface area of the tissue sample tothe blades. If a sample block contains multiple tissue samples, it isgenerally desirable to orient the sample block so that the tissuesamples are all at the same approximate depth with respect to the blade.

Any device or method that determines the depth and general mount angleof the tissue sample may be used. In one embodiment, an optical imagingsystem is used. This may include optical scanning devices using, e.g.,focused light beams or lasers. Other methods and devices for determiningthe location of the tissue sample, such as RF waves, sonar, radar waves,X-rays, magnetic resonance, interferometers, etc., may also be used. Inone embodiment, the optical imaging system locates the position andorientation of the tissue sample in the sample block in sufficientdetail to permit the system controller to determine the desiredorientation of the sample relative to the blade. Once the sample isoptically scanned, the resulting data may be sent to the systemcontroller, which processes the data in order to determine theappropriate orientation of the sample block.

Additional sensors may also be provided before the sample block ispresented to the blades. In one embodiment, a metal detector is providedwhich detects the presence of metal in the sample, which could damagethe blade. If metal is detected, the device may either alert thetechnician, automatically stop, or both.

In step 108, portions of the oriented sample block are removed to exposethe embedded tissue sample. To do this, in one embodiment, the holdingassembly moves the sample block to a blade assembly. The holdingassembly may then cycle over the blade assembly as many times asrequired to reach the depth of the tissue sample, as determined in step106. Each time the holding assembly cycles across the blade assembly,the holding assembly may incrementally move closer to the blade,permitting the blade to cut a disposable slice. Alternately, the bladeassembly may cycle over the sample block and may incrementally movecloser to the tissue sample with each cycle. The sample slices acquiredduring this step are typically discarded, preferably to abiologically-safe holding area.

The blade of the blade assembly may be made of any material havingadequate hardness to cut the sample. Typically, the blade will be madeof hardened spring steel. Alternatively, a cutting wire of narrow gaugeor carbon fiber may be used, or the blade may contain diamond edges, orthe blade may be made of surgical stainless steel.

Although the term “blade” is used generally to describe the componentresponsible for actually making the slice, it is understood that othermechanisms, devices, or components that accomplish this function couldbe substituted where their equivalence is readily apparent to one ofordinary skill. For example, cutting wires fall within the meaning ofthe term “blade” as used herein.

The blade may be continuous or discontinuous. In one embodiment, acontinuous blade is supplied in a blade supply canister, incrementallyadvanced during the operation, and stored on a blade take-up canister.The continuous blade may be continuous roll of any suitable bladematerial. The blade assembly may be driven by a blade supply motor.

The blade may be advanced at predetermined intervals, such as the numberof slices the particular section of blade has made. In anotherembodiment, the blade may advance when the sample block is changed.Other suitable criteria may also be use in order to ensure that theblade produces histologic grade slices. The blade may be incrementallyadvanced automatically, or it may be done manually by the technician.

Blade stock is accordingly incrementally rewound on spindles in theblade take-up canister. When the blade stock runs out, the empty bladesupply canister is replaced with a fresh blade supply canister, and theused blade is discarded.

In one embodiment, two or more blade assemblies may be provided. Thefirst blade assembly may be used to make the initial “rough” slices toexpose the tissue sample, and a second blade assembly may be providedmake the actual histologic grade slice or section. Providing at leasttwo blade assemblies reduces the overall wear on the blade that makesthe histologic grade slice by reducing the number of slices that it isrequired to make. This increases the overall life of the blade andreduces the downtime for blade replacement. Additional blade assembliesmay be provided as necessary, and the blades may be of similar ordifferent materials.

In an alternate embodiment, steps 106 and 108 may be performedsimultaneously. In this embodiment, the slices that are removed from thesample block and monitored by a sensor. Slices are removed until thesensor determines that a sufficient cross-sectional area of the tissuesample is included in each slice. After this determination is made,histological grade slices are then produced.

In step 110, histologic grade slices are produced from sample blocksthat have been brought to the desired depth for producing histologicgrade slices. In one embodiment, where multiple blade assemblies areprovided, the holding assembly advances the sample block toward thefinal blade by a predetermined amount after each cycle, and a given orpre-set number of histologic grade slices are automatically taken fromthe sample block's working surface.

In step 112, the histologic grade slice taken from the sample block isthen applied directly to a transfer roller mechanism. At least onetransfer roller for “picking up” the histologic grade slice andtransferring it to a slide is provided. The purpose of the transferroller mechanism is to capture histologic grade slices from the bladeassembly and convey them to slides while reorientating the slices. In apreferred embodiment, the slices are reoriented from a generallyvertical position to a generally horizontal orientation. In the process,the slices are softened so that they flatten and then smoothly transferto the slide. One of the functions of the transfer roller mechanism,therefore, is to simulate the effect of the warm water bath on a givensample slice. An attractive force, such as negative pressure (a vacuum),may be used to help capture the slices, and a repulsive force, such aspositive pressure, may be used to help release sample slices from thetransfer roller mechanism. Other forms of force, such as electrical,magnetic, electrostatic, and chemical forces, may be used to aid increating the attractive or repulsive force between the slice and thesurface of the transfer roller.

In one embodiment, the transfer roller mechanism includes two transferrollers 210 and 220. Such an embodiment is shown in FIG. 2. Firsttransfer roller 210, which is located near second blade assembly 205,secures and takes control of a histologic grade slice (not shown) fromsample block 200 as soon as that histologic grade slice begins to leavesecond blade assembly 205. To do this, the rotational speed of firsttransfer roller 210 may be set to match the linear motion of the holdingassembly 240 relative to second blade assembly 205. Further, asdiscussed above, the transfer rollers can either generate an attractiveforce or can generate a repulsive force over a portion of theircylindrical surface, or over their entire cylindrical surface. This maydepend upon the stage of rotation of the transfer roller. Theapplication of an attractive force, which may be in the form of negativepressure, aids in picking up each histologic grade slice from secondblade assembly 205, and also aids in spreading the slice smoothly in itslongitudinal dimension. Finally, a repulsive force, which may be in theform of positive air pressure, can assist in the release, or transfer,of the histologic grade slice onto a subsequent transfer roller or ontoslide 250 which may be located on slide conveyer 230.

Additional transfer rollers may be provided as necessary.

The surface of the transfer rollers may also be temperature controlled,including being heated or cooled. This temperature may vary depending onthe support medium that surrounds the sample. In one embodiment, thesurface of the transfer rollers are temperature controlled to atemperature sufficient to induce flattening of the support medium andtissue section. This temperature may be, for example, about 98° F.

Further, the transfer rollers may be coated with a non-stick material,such as titanium, urethane, Teflon™, nylon, or other suitable material.The surface of the transfer rollers may be porous, facilitating theadhesion, flattening, and release of the sample slice through theapplication of negative and positive pressure.

In an alternative embodiment, the sample slice is floated on a watersurface as part of the process for smoothing the slice and transferringit to a slide. The slice may be received by the water surface directlyfrom the blade and then picked up from the water by a transfer roller,or the transfer roller which receives the slice cut from the sample mayplace the slice onto the surface of the water. In either case,attractive and repulsive forces may assist as described above.

Referring again to FIG. 1, in step 114, the histologic grade slice istransferred to a suitable receiving medium, which may be a slide. Thereceiving medium will typically have at least one planar surface. In oneembodiment, slides are fed from a slide dispenser and are printed tocorrespond to a given sample block and the number of slide samplesrequired of that sample block. Once printed, the slides are advanced tothe second transfer roller. In one embodiment, the slide is moved on aslide conveyor, which holds each slide independently of any other slideand in the process, cycles slides under the second transfer roller. Thelinear motion of the slide conveyor is timed to match the rotationalspeed of the second transfer roller, which, as discussed above, is alsoadjusted to match the rotational speed of the first transfer roller.

Minor adjustments to the slide may be made automatically as the slideapproaches the final transfer roller. This may include automaticadjustments to the speed, positioning, and orientation of the slide, sothat the histologic grade slice may be properly positioned on the slide.Additional sensors, including an optical imaging system, may be providedto determine the location of the sample slice relative to a slide andthis information may be used to adjust the slide position. In anotherembodiment, manual adjustments may also be made by the technician.

In another embodiment, the slice may be secured in film or tape as thereceiving medium. Suitable tape is disclosed in U.S. Pat. No. 5,746,855,which is hereby incorporated by reference in its entirety. In thisembodiment, the sample may be transferred from the first or secondtransfer roller to the tape in a similar fashion as described above.

Prior to passing under the final transfer roller, the slide may bemisted with distilled water. This misting wets the mounting surface ofthe slide to enhance the surface tension proprieties of both the slideand the histologic grade slice, forming a fluid bond between the surfaceof the slide and the surface of the histologic grade slice.

Other fluids may be misted on the surface of the slide. Generally, thesefluids will have surface tension properties that permit a tissue slicein the support medium to adhere and spread on the surface of a slidewithout wrinkling, stretching, or tearing. The fluid will be selectedfrom a group of fluids that will neither dissolve the tissue supportmedium nor the slide, nor will perceptibly distort the tissue slice orslide.

In an alternate embodiment, the surface of the histologic grade slicethat will be in contact with the surface of the slide may be misted witha medium as described above.

In addition, the slide may be coded with information regarding thetissue sample. This information may include the information entered bythe technician during the preparation of the sample block, and mayfurther include information regarding the sample slice sequence whereseveral sample slices are taken (e.g., “slice 7 of 20”). Thisinformation may be bar coded, and may be printed on the slide directly,or printed on a label and then affixed to the slide.

As the final transfer roller begins to interface with a slide, arepulsive force, such as controlled positive air pressure, may assist inthe release of the histologic grade slice sample from the transferroller onto the wet surface of the slide. The histologic grade sliceadheres to the slide and moves beyond the transfer roller.

Following the transfer of the histologic grade slice to the slide, apressure roller may be provided to apply light pressure to the sample onthe slide to further flatten the histologic grade slice and to promoteadhesion to the slide surface.

In optional step 116, any support medium that overhangs the slide may beremoved. The slides may pass through the stripper assembly, which mayhave stripper fins that shift into contact with a slide, where adescending vertical motion against the edges the slide strips away, ortrims, the support medium excess, with the excess being removed andautomatically disposed of.

In step 118, the slides are discharged from the device. The slides thenexit the device and may be either manually picked-up as they exit or anaccumulating extension can be added to the exit conveyor to increasecapacity. In one embodiment, the slides advance to the end of the slideconveyor and are then stacked 90 degrees incrementally onto the slideaccumulation conveyor.

The finished slides may be conveyed to any other type of unit, such as adryer, a stainer, image capture device or any other analytic device. Theslide accumulation conveyor may have a final code scanner which checksthe slide code sequence and automatically matches it with the sampleblock order of process and records it as complete.

Optionally, the technician may have the ability to manually over-ridethe cycle of the slide accumulation conveyor. This ability will beuseful at the end of a processing run where the technician wants tounload finished slides from the accumulation exit conveyor when thereare no subsequent sample blocks to be processed.

In step 120, the sample block is released by the holding assembly. Inone embodiment, the holding assembly moves the sample block to thedischarge chute. The discharge chute can maintain the sample blocks inthe order in which they were processed. The technician may be able torelease the sample blocks by pressing a lever, or they may beautomatically returned to a holding area.

The sample block chute optionally provides a biologically-safe andconvenient means of disposal. The sample blocks may be released into acollecting device, which may be later retrieved by personnel for properdisposal.

A preferred embodiment of the present invention is shown in FIGS. 3-5,which depicts the system for automatically producing tissue slides.System 300 is a preferred embodiment only, and the present invention isnot limited to this preferred embodiment. The arrangement of elements ofthe system in FIGS. 3-5 in no way limits the present invention. It iswithin the contemplation of the present invention to arrange or modifyelements of the system in accordance with other design requirements,such as, inter alia, the amount of space available to accomplish themethod of this invention.

Referring to FIGS. 3 and 4, System 300 includes sample block loadingarea 302 and sample block identification area 304. In sample blockloading area 302, sample blocks may be manually or automatically placedinto a sample block dispenser (not shown). In the embodiment shown, thesample blocks are placed in sample block dispenser (not shown) such thattheir working surfaces are oriented downward. Sample block dispenser(not shown) may be positioned over a conveyor assembly for transferringthe sample blocks to sample block identification area 304. As eachsample block is added to the in-feed conveyor, its identificationinformation is manually entered and stored in system controller 316, orthe information may be automatically entered into the system controllerby an optical scanner (not shown) that scans a pre-placed code on thesample block's plastic housing. This information may include, interalia, patient's name, type of sample (i.e., what organ the sample camefrom), the number of slides that are to be made, clinical diagnosis, orany other relevant information.

System controller 316 may be any suitable microprocessor-basedcontroller. In one embodiment, an Xpert 8 series computer, manufacturedby Siemens AG, München, Germany, may be used as the controller. Inanother embodiment, a Scenic series computer, also manufactured bySiemens AG, may be used. In still another embodiment, a Pentium™-seriesmicroprocessor, manufactured by Intel, Inc., may be used.

The sample block code information may be displayed on display screen330. Display screen 330 may be any suitable display means, includingflat-panel displays, CRTs, LCD displays, and touch-screens. In oneembodiment, a touch-screen is used to display information and tosimultaneously serve as an input means. Other input means, such askeyboards, keypads, etc., may also be used. In one embodiment, SICOMPIMP 100, manufactured by Siemens AG, München, Germany, is used as atouch-screen display. Other suitable displays, including the MCM-seriesmonitor, also available from Siemens AG, and other input means may alsobe used.

In one embodiment, display screen 330 may be used to display theprogress of a particular sample block. Once the sample block is scanned,display screen 330 may present an image of the embedded tissue samplefor the technician to view. This image may be presented in a perspectiveview, and the technician may be able to rotate the image. The intendeddepth of the slices may also be displayed.

Display screen 330 preferably also allows the technician to modifysystem parameters. For instance, the technician may have the ability tomodify the temperature of either or both transfer rollers, the speed ofthe various conveyors, the oscillation speed and distance of the holdingmechanism during slicing, etc.

Sample blocks may or may not include their own identification code.However, it is preferred that by the time a given sample block reachesthe first processing station, its identification information and thesequence in which it was placed on the conveyor is registered in systemcontroller 316. This information identifies products (slides), matchessequence number of the sample with codes related to the sample, anddrives slide printer 328, which may be an ink jet printer, to printsample-related information on the slides. Thus, in the preferredembodiment, before the processing is initiated, system controller 316matches the sequence number of the sample block about to undergoprocessing with the expected sample block's registered identificationinformation.

After suitable identification of the sample block, the sample block istransferred to a first processing station. In the embodiment shown, thesample blocks are transferred by lug conveyor, which facilitatespositive identification of the sample blocks.

At the first processing station, the sample blocks are secured by theholding assembly. In one embodiment, robotic clamp assembly 350 is usedto secure the sample block. Robotic clamp assembly 350 may includetraditional clamps, or may include vacuum clamps.

Robotic clamp 350 captures the leading sample block in queue. In oneembodiment, robotic clamp 350 takes control of the sample block bygrasping the length dimension sides of its plastic holder and moves itto a second processing station where it is scanned for tissue samplecoordinates. In another embodiment, robotic clamp 350 uses negativepressure to secure the sample block.

Following clamping, the location of the tissue sample within theparaffin block is determined by optical imaging system 348. Opticalimaging system 348 the depth and general mount angle of the tissuesample within the paraffin block portion of the sample block. Once theposition of the tissue sample is established and entered into the systemcontroller 316, robotic clamp 350 adjusts the paraffin block's workingsurface relative to blades at the next processing station to level thetissue sample and formulate its depth from the working surface of thesurface of the paraffin block.

In a preferred embodiment, the robotic clamp assembly has the abilityto, automatically adjust its position (and thereby the position of thesample block) to present the best orientation of paraffin block workingsurface to both of the blade assemblies further on in the process. Inthis process, target coordinates which identify the center of the tissuesample relative to the plane of the paraffin block's working surface areobtained based upon the located position of the tissue sample.

After determination of the location of the tissue sample at the secondprocessing station, the sample block is moved to blade assemblies forcutting. In the embodiment shown, two blade assemblies for cutting intothe sample block are provided: first blade assembly 346 for roughcutting to remove unwanted material from the tissue block; and secondblade assembly 342 to produce histologic grade slices. Blades to cut thesample block are provided at each of these blade assemblies 346 and 342by blade supply canisters 306 and 310, respectively. In the embodiment,blades (not shown) are several hundred inches long and are fed from thesame type of canister and wound on the same type spindle. Blades (notshown) may be guided across their cutting assembly surfaces by a seriesof guide rollers (not shown).

The blades of first blade assembly 346 and second blade assembly 342 areeach stored within the respective blade supply canisters, 306 and 310.The blade may be continuous roll of blade material. Further, both bladeassemblies 346 and 342 may be driven by blade supply motor 308. A bladetake-up canister may be provided for each blade supply canister 306 and310 to received the used blade.

The blades may be any suitable cutting material. In one embodiment,hardened spring steel is used as a blade. Other blade materials,including carbon fiber, diamond edged strip, or surgical stainlesssteel, may alternatively be fed from blade supply canister 306 or 310and wound into the respective take-up canister.

The blades of both first and second blade assemblies 346 and 342 may beincrementally advanced at predetermined intervals, as discussed above.For example, the blade may be advanced for each new sample block, or itmay be advanced after a predetermined number of slices. In oneembodiment, as soon as a sample block is sliced to tissue depth by firstblade assembly 346, the blade in first blade assembly 346 may advance,and accordingly, as soon as histologic grade slices are produced atsecond blade assembly 342, the blade in second blade assembly 342 mayalso advance.

Blade stock is accordingly incrementally rewound on spindles in theblade take-up canisters (not shown). When either blade runs out, theempty blade supply canister is replaced with a fresh blade supplycanister. The used blade is discarded. The blade canisters may bereplacement items, with empty canisters being refilled and spindles alsobeing reusable. The blade canister system provides for the easy disposalof medical waste. For instance, once the used blade is wound on theblade take-up canister, the blade take-up canister can be autoclaved andthen discarded in the normal trash.

In another embodiment, standard fixed blades of a suitable material maybe used. These materials may include the same materials used for thecontinuous blade. These fixed blades may be replaced automatically, orthey may be replaced manually by the technician.

When the sample block is moved to first blade assembly 346, the angle ofrobotic clamp assembly 350 is automatically adjusted (guided by theinput of the tissue sample coordinates) relative to first blade assembly346. In one embodiment, robotic clamp 350 moves the sample block pastfirst blade assembly 346 to cut the sample block. An equivalentmechanism in which first blade assembly 346 moves past a stationarysample block is also within the contemplation of this invention, as areembodiments where both first blade assembly 346 and sample block move ina coordinated fashion. Robotic clamp 350 may cycle, moving across firstblade assembly 346 to cut successive slices from the sample block untilthe tissue sample is exposed and ready to yield useable histologic gradeslices. Sample slices produced by these cycles fall onto accumulationexit conveyor 312 and are transported into paraffin scrap bin 314 fortemporary storage and disposal.

Once the surface of the sample block has been cut to a desired depth forproducing histologic grade slices in preparation for slicing, roboticclamp 350 is driven a pre-set distance to move the sample block tosecond blade assembly 342. Robotic clamp assembly 350 then automaticallyorientates to the same coordinates for a given sample block and moves toa position adjacent to blade assembly 342 where a given number ofhistologic grade slices are automatically taken from the paraffinblock's working surface.

System controller 316 retains the information that enables thecontinuity of the slicing operation from first blade assembly 346 tosecond blade assembly 342. The difference is that slices taken at firstblade assembly 346 are discarded into paraffin scrap bin 314, whileslices taken at second blade assembly 342 are applied directly to firsttransfer roller 502 of transfer roller mechanism 344.

Transfer roller mechanism 344 is further shown in FIG. 5. First transferroller 502 is positioned tangent to and above second transfer roller504. Both first and second transfer rollers 502 and 504 may be coatedwith titanium, urethane, or other materials. Further, the surfaces oftransfer rollers 502 and 504 may be coated with a porous material. Asdiscussed above, both first and second transfer rollers 502 and 504 mayhave the ability to generate attractive and repulsive forces between thesurface of the transfer roller and the slice, and may do thisindependently of each other and over all or a portion of the surface ofeach roller at any given time or position of rotation.

First transfer roller 502 is positioned directly below second bladeassembly 342. First transfer roller 502 begins to pick-up and takecontrol of a given histologic grade slice as soon as that slice beginsto leave second blade 342. The rotational speed of first transfer roller502 is timed to match the linear motion of robotic clamp 350 relative tosecond blade assembly 342.

First and second transfer rollers 502 and 504 are part of the mechanismthat replicates the action of the technician's hand in pulling thehistologic grade slice away from the blade and placing it in the waterbath. First and second transfer rollers 502 and 504 replace thefunctions of moving histologic grade slices from the edge of the bladeto the water bath and then from the water bath onto the empty slide.

Second transfer roller 504 is positioned tangent to and below transferroller 502. The purpose of second transfer roller 504 is to be theinterface between first transfer roller 502 and the slides. In theprocess, the tissue sample is inverted, further smoothed, located andapplied to a corresponding slide.

Slide 514, or other suitable receiving medium, is fed from slidedispenser 332 and is printed to correspond to a given sample block andthe number of slide samples required of that sample block. Once printed,slides are incrementally advanced on slide conveyor 406 which holds eachslide independently of any other slide, and in the process, cycles codedslides under second transfer roller 504. The linear motion of slideconveyor 406 is timed to match the rotational speed of second transferroller 504 which in turn is automatically adjustable to match therotational speed of first transfer roller 502. As second transfer roller504 begins its interface with slide 514, a repulsive force, which may bein the form of controlled positive pressure, aids the release of thetissue sample from second transfer roller 504 to slide 514's surface.

Referring again to FIG. 3, sprayer head 336, sprayer pump 320 and spraytank 324 are provided to mist the incoming slide with distilled water,or any other suitable material, to enhance the bonding between thehistologic grade slice and slide 514.

Optionally, an optical scanner (not shown) focused on second transferroller 504 verifies the location of the tissue sample by measuring itscalibrated transverse and circumference center point coordinate sites.This information is input to system controller 316 to transverselyadjust the entry of slide 514 relative to second transfer roller 504 andthen control the timed release of the sample slice to slide 514. Secondtransfer roller 504 delivers the sample slice to slide 514. An exhaustof low pressure filtered air may assist in this transition. Thetransition position of slide 514 is controlled and based on thepredetermined location of the center of the tissue sample on firsttransfer roller 502 and/or second transfer roller 504. Preferably, onlyone sample slice is on any of the transfer rollers at any given time,with the exception that for a transfer roller assembly with more thantwo rollers, a subsequent slice can begin to be applied to firsttransfer roller 502 at the same time as the slice on second transferroller 504 is being applied to its slide.

Slide dispenser 332 may be located on the front side of system 300.Slides (not shown) may be manually loaded into slide dispenser 332.Slide dispenser 332 may be a vertical canister mounted directly overslide conveyor 406. Slide dispenser 332 releases one slide (not shown)for each cutting cycle. The release may be managed by system controller316 and may be triggered by an optical scanner provided in sample blockidentification area 304 that reads the code on an incoming sampleblocks.

In one embodiment, slide dispenser 332 may be provided with a sensor(not shown) for sensing when slide dispenser 332 is running low onslides. This sensor may cause a warning light or other suitable indictorto allow the technician to replenish the slides. If the slide dispenser332 runs out of slides, system 300 may automatically stop operation.

In another embodiment, other suitable receiving media may be used inplace of the slides, such as plastic or film, as discussed above.Typically, the receiving medium will have at least one planar surface.

Slide dispenser 332 may operate as follows. Slide dispenser 332automatically feeds individual slides for labeling. When system 300 isready to process a given sample block, the corresponding slides will besequentially labeled with some or all of this information. System 300will track each sample block and corresponding slide or slides as theyprogress.

Activation of slide dispenser 332 may be automatic after a given sampleblock code is read and entered, or it may be under the manual control ofthe technician. The number of slides prepared for a given sample blockmay be determined from an item in the sample block code or it may bemanually entered or altered by an technician.

After a tissue sample is applied to the surface of a slide, the slidesadvance to the end of slide conveyor 406 and may be indexed 90 degreesincrementally onto the slide accumulation conveyor. The slides indexbased on the ongoing process cycle where each time a process is finishedand tissue sample from second transfer roller 504 applied to the surfaceof a corresponding slide, the accumulation exit conveyor indexes once.The finished slides can be manually picked up as they exit or anaccumulating extension can be added to the exit conveyor to increasecapacity or they can be conveyed to any other type of unit—for example,a dryer.

The slide accumulation conveyor may have a final code scanner (notshown) which checks the slide code sequence and automatically matches itwith the sample block order of process and records it as complete. Thetechnician may have the ability to manually override the cycle of theslide accumulation conveyor.

Sample block exit chute 318 is provided for the sample block to bereleased into when the requested or requisite number of histologic gradeslices have been achieved. The sample block is released into exit chute318 in the sequence in which they are processed.

As discussed in the background, microtomes generally operate with avertical orientation. That is, once the sample block, is locked into themicrotome's clamp and orientated by the technician to achieve the bestworking surface orientation, the slicing process (sample block relativeto razor blade) is vertical. The present invention, however, may operatewith the sample block having either a vertical or a horizontalorientation. Having a horizontal orientation yields several benefits,including the fact that sample blocks enter system 300 in exactly thesame way as for the vertical version. However, once within the clampingseries they are be shifted horizontally with the sample block's workingsurface oriented upwards. The slicing to depth and subsequent slices ofthe actual samples would also be horizontal with the sample block belowand parallel to the blade assembly above.

With a horizontal orientation, the transfer roller mechanism will notneed to reorientate the sample slices from a generally vertical to ahorizontal plane. Their purpose is solely to move the sample slice fromthe sample block's working surface in a horizontal plane directly onto aslide. This contrasts to the vertical orientation, where the transferroller mechanism must also reorient the sample slice from a verticalorientation to a horizontal orientation for the slide.

While the invention has been described in connection with preferredembodiments and examples, it will be understood by those skilled in theart that other variations and modifications of the preferred embodimentsdescribed above may be made without departing from the scope of theinvention. Other embodiments will be apparent to those skilled in theart from a consideration of the specification or practice of theinvention disclosed herein. It is intended that the specification isconsidered as exemplary only, with the true scope and spirit of theinvention being indicated by the following claims.

1. An apparatus for applying thin sections of a tissue sample to areceiving medium comprising: a blade assembly for slicing thin sectionsfrom a tissue sample; a plurality of transfer rollers sequentiallyarranged in tangential proximity to each other, such that said thinsection in contact with a surface of one transfer roller will betransferred to the surface of the sequentially successive transferroller; wherein a first sequential transfer roller of said plurality oftransfer rollers is oriented in proximity to said blade assembly so thatsaid thin section sliced from said tissue sample will contact thesurface of said first sequential transfer roller; a receiving mediumdisposed in tangential proximity to a final sequential transfer rollerof said plurality of transfer rollers so that said thin section on thesurface of said final sequential transfer roller will be transferred tosaid receiving medium in a substantially smooth and flat configuration;a first blade assembly for slicing said tissue sample to expose aworking surface; and a second blade assembly for producing said thinsections.
 2. The apparatus of claim 1, wherein one or more of said firstand second blade assemblies comprises: a blade supply canister forproviding a continuous blade of a predetermined length; and wherein saidcontinuous blade is advanced from said blade supply canister atpredetermined intervals.
 3. An apparatus for automatically producingtissue slides from a tissue sample within a sample block: a holdingassembly for manipulating said sample block; a blade assembly forslicing thin sections from said sample block; a transfer rollermechanism for transferring said thin section in contact with a surfaceof a transfer roller to a receiving medium; a controller; and an opticalimaging system for locating said tissue sample within said sample block;wherein said controller determines an optimum orientation of said sampleblock with respect to said blade assembly.
 4. An apparatus forautomatically producing tissue slides from a tissue sample within asample block comprising: a holding assembly for manipulating said sampleblock; a blade assembly for slicing thin sections from said sampleblock; a blade supply canister for providing a continuous blade of apredetermined length; a transfer roller mechanism for transferring saidthin section in contact with a surface of a transfer roller to areceiving medium; and a controller; wherein said continuous blade isadvanced from said blade supply canister at predetermined intervals.